The invention relates to a key structure adopted for use on a larger size key, and particularly to a key that can generate an indicating light to achieve effective depressing movements and indicate current key conditions.
A keyboard generally consists of a plurality of keys to serve as a communication interface to an electronic data processing apparatus (such as a computer). Keyboard structures are constantly evolving and new features and functions continuously added. For instance:
First, every key on the keyboard inputs a preset signal when depressed once and automatically returns to its original position when released. To make the return movement possible, the general approach is to install a spring under the key. Taking the keyboard of a personal computer as an example, every keyboard has more than one hundred keys, including numeral keys, character keys and function keys. Hence more than one hundred springs have to be installed. Such a design increases costs for the springs, and also increases assembly time. To resolve this problem, some producers have designed an elastic plate with elastic domes corresponding to key positions. The elastic plate is made from material such as rubber by integrated injection forming processes. The rubber has rich elasticity, thus the elastic domes may be used to replace the springs. Through integrated injection forming processes, production costs and assembly time can be greatly reduced.
Second, with a growing number of application software on the market, hot keys are added on the keyboards in addition to the numeral keys, character keys and function keys to facilitate user operations of the application software. For example, to link to networks used to require many steps. Now, through the design of the hot keys, linking to networks can be accomplished by a single push on a selected hot key.
Third, many keyboards have illumination design to enable users to operate easier in circumstances where ambient light is not sufficient. The light sources used are mostly light emitting diodes. Depending on illuminating methods, some illuminating keys adopt constant lighting while others adopt an on/off approach based on key operations.
The Hot keys mentioned above generally have a larger size than conventional keys. The elastic plate to provide elastic force for the Hot Keys should also have elastic domes of a larger size. While this can easily be done through injection forming process, the larger size of the elastic dome made from rubber causes reduced flexibility (the elastic dome becomes softer). As a result, return elasticity decreases. When using a single elastic dome to match a key of a larger size, because the elastic becomes softer, the depression location on the key of a user""s finger can affect the compression direction of the elastic dome and result in ineffective depression.
Moreover, for illuminating keys, the light sources are generally located between the circuit board and elastic plate. To design keys that are turned on or off depending on key operations, the light sources must match key locations. However the elastic plate tends to obstruct light projection of the light sources and causes reduction of light intensity. U.S. Pat. No. 5,612,692 discloses a design for illuminating keys. The illuminating key includes a key cap and an elastic dome located under the key. That patent has a complex structure, and the light source is located on a position biased to the key. Only a small portion of the key is illuminated. Moreover, light generated by lighting elements has to pass through the media of the elastic dome and key cap. Thus the illuminating effect is undesirable.
The conventional techniques set forth above either have complex structures and designs for larger size or illuminating keys, cannot provide effective depression, or have complicated manufacturing processes and higher production costs. The higher costs and complicated production processes become huge disadvantages for the electronic industry, which has to wrestle with the challenges of continuous price reduction and increasing demands for shorter research and development cycles. Improved designs for keys to simplify production processes and reduce production costs are critical technical issues yet to be overcome.
The primary object of the invention is to provide a key structure for larger size and illuminating keys.
The key structure according to the invention consists of a key cap and two elastic domes. The key cap has a bottom rim which has two lugs located on two sides thereof The two elastic domes hold and support the lugs of the key cap in a non-depressed position. The two elastic domes have different compression displacements and flexibility to allow the cap to move in a selected direction to reach a depressed position and accomplish signal input.
The key structure according to the invention has a lighting element on the circuit board located between two elastic domes to allow light to directly project through the key cap without the obstruction of the elastic domes.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. The drawings are only to serve for reference and illustrative purposes, and are not intended to limit the scope of the invention.